Method and device for configuring sl harq rtt timer in nr v2x

ABSTRACT

Provided are a method for performing wireless communication by a first device, and a device for supporting same. The method may comprise: obtaining a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receiving, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receiving, from the second device through the PSSCH, the second SCI and data; determining a value of a SL DRX hybrid automatic repeat request (HARD) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and starting the SL DRX retransmission timer.

CROSS-REFERENCE TO RELATED APPLICATION(S)

Pursuant to 35 U.S.C. § 119(e), this application claims the benefit of U.S. Provisional Patent Application No. 63/274,016, filed on Nov. 1, 2021, the contents of which are all hereby incorporated by reference herein in their entireties.

TECHNICAL FIELD

This disclosure relates to a wireless communication system.

BACKGROUND

Sidelink (SL) communication is a communication scheme in which a direct link is established between User Equipments (UEs) and the UEs exchange voice and data directly with each other without intervention of an evolved Node B (eNB). SL communication is under consideration as a solution to the overhead of an eNB caused by rapidly increasing data traffic. Vehicle-to-everything (V2X) refers to a communication technology through which a vehicle exchanges information with another vehicle, a pedestrian, an object having an infrastructure (or infra) established therein, and so on. The V2X may be divided into 4 types, such as vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-network (V2N), and vehicle-to-pedestrian (V2P). The V2X communication may be provided via a PC5 interface and/or Uu interface.

Meanwhile, as a wider range of communication devices require larger communication capacities, the need for mobile broadband communication that is more enhanced than the existing Radio Access Technology (RAT) is rising. Accordingly, discussions are made on services and user equipment (UE) that are sensitive to reliability and latency. And, a next generation radio access technology that is based on the enhanced mobile broadband communication, massive Machine Type Communication (MTC), Ultra-Reliable and Low Latency Communication (URLLC), and so on, may be referred to as a new radio access technology (RAT) or new radio (NR). Herein, the NR may also support vehicle-to-everything (V2X) communication.

SUMMARY

In one embodiment, provided is a method for performing wireless communication by a first device. The method may comprise: obtaining a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receiving, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receiving, from the second device through the PSSCH, the second SCI and data; determining a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and starting the SL DRX retransmission timer.

In one embodiment, provided is a first device adapted to perform wireless communication. The first device may comprise: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers. The one or more processors may execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; control the one or more transceivers to receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); control the one or more transceivers to receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.

In one embodiment, provided is a processing device adapted to control a first device. The processing device may comprise: one or more processors; and one or more memories operably connected to the one or more processors and storing instructions. The one or more processors may execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a structure of an NR system, based on an embodiment of the present disclosure.

FIG. 2 shows a radio protocol architecture, based on an embodiment of the present disclosure.

FIG. 3 shows a structure of a radio frame of an NR, based on an embodiment of the present disclosure.

FIG. 4 shows a structure of a slot of an NR frame, based on an embodiment of the present disclosure.

FIG. 5 shows an example of a BWP, based on an embodiment of the present disclosure.

FIG. 6 shows a procedure of performing V2X or SL communication by a UE based on a transmission mode, based on an embodiment of the present disclosure.

FIG. 7 shows three cast types, based on an embodiment of the present disclosure.

FIG. 8 shows a method for an RX UE to perform a power saving operation based on SCI, based on an embodiment of the present disclosure.

FIG. 9 shows a procedure for an RX UE and/or a TX UE to perform SL communication based on a SL DRX configuration, based on an embodiment of the present disclosure.

FIG. 10 shows a method for performing a power saving operation based on resource reservation information included in SCI, based on an embodiment of the present disclosure.

FIG. 11 shows a method for performing wireless communication by a first device, based on an embodiment of the present disclosure.

FIG. 12 shows a method for performing wireless communication by a second device, based on an embodiment of the present disclosure.

FIG. 13 shows a communication system 1, based on an embodiment of the present disclosure.

FIG. 14 shows wireless devices, based on an embodiment of the present disclosure.

FIG. 15 shows a signal process circuit for a transmission signal, based on an embodiment of the present disclosure.

FIG. 16 shows another example of a wireless device, based on an embodiment of the present disclosure.

FIG. 17 shows a hand-held device, based on an embodiment of the present disclosure.

FIG. 18 shows a vehicle or an autonomous vehicle, based on an embodiment of the present disclosure.

DETAILED DESCRIPTION

In the present disclosure, “A or B” may mean “only A”, “only B” or “both A and B.” In other words, in the present disclosure, “A or B” may be interpreted as “A and/or B”. For example, in the present disclosure, “A, B, or C” may mean “only A”, “only B”, “only C”, or “any combination of A, B, C”.

A slash (/) or comma used in the present disclosure may mean “and/or”. For example, “A/B” may mean “A and/or B”. Accordingly, “A/B” may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C” may mean “A, B, or C”.

In the present disclosure, “at least one of A and B” may mean “only A”, “only B”, or “both A and B”. In addition, in the present disclosure, the expression “at least one of A or B” or “at least one of A and/or B” may be interpreted as “at least one of A and B”.

In addition, in the present disclosure, “at least one of A, B, and C” may mean “only A”, “only B”, “only C”, or “any combination of A, B, and C”. In addition, “at least one of A, B, or C” or “at least one of A, B, and/or C” may mean “at least one of A, B, and C”.

In addition, a parenthesis used in the present disclosure may mean “for example”. Specifically, when indicated as “control information (PDCCH)”, it may mean that “PDCCH” is proposed as an example of the “control information”. In other words, the “control information” of the present disclosure is not limited to “PDCCH”, and “PDCCH” may be proposed as an example of the “control information”. In addition, when indicated as “control information (i.e., PDCCH)”, it may also mean that “PDCCH” is proposed as an example of the “control information”.

In the following description, ‘when, if, or in case of’ may be replaced with ‘based on’.

A technical feature described individually in one figure in the present disclosure may be individually implemented, or may be simultaneously implemented.

In the present disclosure, a higher layer parameter may be a parameter which is configured, pre-configured or pre-defined for a UE. For example, a base station or a network may transmit the higher layer parameter to the UE. For example, the higher layer parameter may be transmitted through radio resource control (RRC) signaling or medium access control (MAC) signaling.

The technology described below may be used in various wireless communication systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and so on. The CDMA may be implemented with a radio technology, such as universal terrestrial radio access (UTRA) or CDMA-2000. The TDMA may be implemented with a radio technology, such as global system for mobile communications (GSM)/general packet ratio service (GPRS)/enhanced data rate for GSM evolution (EDGE). The OFDMA may be implemented with a radio technology, such as institute of electrical and electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, evolved UTRA (E-UTRA), and so on. IEEE 802.16m is an evolved version of IEEE 802.16e and provides backward compatibility with a system based on the IEEE 802.16e. The UTRA is part of a universal mobile telecommunication system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is part of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTE uses the OFDMA in a downlink and uses the SC-FDMA in an uplink. LTE-advanced (LTE-A) is an evolution of the LTE.

5G NR is a successive technology of LTE-A corresponding to a new Clean-slate type mobile communication system having the characteristics of high performance, low latency, high availability, and so on. 5G NR may use resources of all spectrum available for usage including low frequency bands of less than 1 GHz, middle frequency bands ranging from 1 GHz to 10 GHz, high frequency (millimeter waves) of 24 GHz or more, and so on.

For clarity in the description, the following description will mostly focus on LTE-A or 5G NR. However, technical features according to an embodiment of the present disclosure will not be limited only to this.

FIG. 1 shows a structure of an NR system, based on an embodiment of the present disclosure. The embodiment of FIG. 1 may be combined with various embodiments of the present disclosure.

Referring to FIG. 1 , a next generation—radio access network (NG-RAN) may include a BS 20 providing a UE 10 with a user plane and control plane protocol termination. For example, the BS 20 may include a next generation-Node B (gNB) and/or an evolved-NodeB (eNB). For example, the UE 10 may be fixed or mobile and may be referred to as other terms, such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), wireless device, and so on. For example, the BS may be referred to as a fixed station which communicates with the UE 10 and may be referred to as other terms, such as a base transceiver system (BTS), an access point (AP), and so on.

The embodiment of FIG. 1 exemplifies a case where only the gNB is included. The BSs 20 may be connected to one another via Xn interface. The BS 20 may be connected to one another via 5th generation (5G) core network (5GC) and NG interface. More specifically, the BSs 20 may be connected to an access and mobility management function (AMF) 30 via NG-C interface, and may be connected to a user plane function (UPF) 30 via NG-U interface.

Layers of a radio interface protocol between the UE and the network can be classified into a first layer (layer 1, L1), a second layer (layer 2, L2), and a third layer (layer 3, L3) based on the lower three layers of the open system interconnection (OSI) model that is well-known in the communication system. Among them, a physical (PHY) layer belonging to the first layer provides an information transfer service by using a physical channel, and a radio resource control (RRC) layer belonging to the third layer serves to control a radio resource between the UE and the network. For this, the RRC layer exchanges an RRC message between the UE and the BS.

FIG. 2 shows a radio protocol architecture, based on an embodiment of the present disclosure. The embodiment of FIG. 2 may be combined with various embodiments of the present disclosure. Specifically, (a) of FIG. 2 shows a radio protocol stack of a user plane for Uu communication, and (b) of FIG. 2 shows a radio protocol stack of a control plane for Uu communication. (c) of FIG. 2 shows a radio protocol stack of a user plane for SL communication, and (d) of FIG. 2 shows a radio protocol stack of a control plane for SL communication.

Referring to FIG. 2 , a physical layer provides an upper layer with an information transfer service through a physical channel. The physical layer is connected to a medium access control (MAC) layer which is an upper layer of the physical layer through a transport channel. Data is transferred between the MAC layer and the physical layer through the transport channel. The transport channel is classified according to how and with what characteristics data is transmitted through a radio interface.

Between different physical layers, i.e., a physical layer of a transmitter and a physical layer of a receiver, data are transferred through the physical channel. The physical channel is modulated using an orthogonal frequency division multiplexing (OFDM) scheme, and utilizes time and frequency as a radio resource.

The MAC layer provides services to a radio link control (RLC) layer, which is a higher layer of the MAC layer, via a logical channel. The MAC layer provides a function of mapping multiple logical channels to multiple transport channels. The MAC layer also provides a function of logical channel multiplexing by mapping multiple logical channels to a single transport channel. The MAC layer provides data transfer services over logical channels.

The RLC layer performs concatenation, segmentation, and reassembly of Radio Link Control Service Data Unit (RLC SDU). In order to ensure diverse quality of service (QoS) required by a radio bearer (RB), the RLC layer provides three types of operation modes, i.e., a transparent mode (TM), an unacknowledged mode (UM), and an acknowledged mode (AM). An AM RLC provides error correction through an automatic repeat request (ARQ).

A radio resource control (RRC) layer is defined only in the control plane. The RRC layer serves to control the logical channel, the transport channel, and the physical channel in association with configuration, reconfiguration and release of RBs. The RB is a logical path provided by the first layer (i.e., the physical layer or the PHY layer) and the second layer (i.e., a MAC layer, an RLC layer, a packet data convergence protocol (PDCP) layer, and a service data adaptation protocol (SDAP) layer) for data delivery between the UE and the network.

Functions of a packet data convergence protocol (PDCP) layer in the user plane include user data delivery, header compression, and ciphering. Functions of a PDCP layer in the control plane include control-plane data delivery and ciphering/integrity protection.

A service data adaptation protocol (SDAP) layer is defined only in a user plane. The SDAP layer performs mapping between a Quality of Service (QoS) flow and a data radio bearer (DRB) and QoS flow ID (QFI) marking in both DL and UL packets.

The configuration of the RB implies a process for specifying a radio protocol layer and channel properties to provide a particular service and for determining respective detailed parameters and operations. The RB can be classified into two types, i.e., a signaling RB (SRB) and a data RB (DRB). The SRB is used as a path for transmitting an RRC message in the control plane. The DRB is used as a path for transmitting user data in the user plane.

When an RRC connection is established between an RRC layer of the UE and an RRC layer of the E-UTRAN, the UE is in an RRC_CONNECTED state, and, otherwise, the UE may be in an RRC_IDLE state. In case of the NR, an RRC_INACTIVE state is additionally defined, and a UE being in the RRC_INACTIVE state may maintain its connection with a core network whereas its connection with the BS is released.

Data is transmitted from the network to the UE through a downlink transport channel. Examples of the downlink transport channel include a broadcast channel (BCH) for transmitting system information and a downlink-shared channel (SCH) for transmitting user traffic or control messages. Traffic of downlink multicast or broadcast services or the control messages can be transmitted on the downlink-SCH or an additional downlink multicast channel (MCH). Data is transmitted from the UE to the network through an uplink transport channel. Examples of the uplink transport channel include a random access channel (RACH) for transmitting an initial control message and an uplink SCH for transmitting user traffic or control messages.

Examples of logical channels belonging to a higher channel of the transport channel and mapped onto the transport channels include a broadcast channel (BCCH), a paging control channel (PCCH), a common control channel (CCCH), a multicast control channel (MCCH), a multicast traffic channel (MTCH), etc.

FIG. 3 shows a structure of a radio frame of an NR, based on an embodiment of the present disclosure. The embodiment of FIG. 3 may be combined with various embodiments of the present disclosure.

Referring to FIG. 3 , in the NR, a radio frame may be used for performing uplink and downlink transmission. A radio frame has a length of 10 ms and may be defined to be configured of two half-frames (HFs). A half-frame may include five 1 ms subframes (SFs). A subframe (SF) may be divided into one or more slots, and the number of slots within a subframe may be determined based on subcarrier spacing (SCS). Each slot may include 12 or 14 OFDM(A) symbols according to a cyclic prefix (CP).

In case of using a normal CP, each slot may include 14 symbols. In case of using an extended CP, each slot may include 12 symbols. Herein, a symbol may include an OFDM symbol (or CP-OFDM symbol) and a Single Carrier-FDMA (SC-FDMA) symbol (or Discrete Fourier Transform-spread-OFDM (DFT-s-OFDM) symbol).

Table 1 shown below represents an example of a number of symbols per slot (N^(slot) _(symb)), a number slots per frame (N^(frame,u) _(slot)), and a number of slots per subframe (N^(subframe,u) _(slot)) based on an SCS configuration (u), in a case where a normal CP is used.

TABLE 1 SCS (15*2^(u)) N^(slot) _(symb) N^(frame,u) _(slot) N^(subframe,u) _(slot) 15 KHz (u = 0) 14 10 1 30 KHz (u = 1) 14 20 2 60 KHz (u = 2) 14 40 4 120 KHz (u = 3) 14 80 8 240 KHz (u = 4) 14 160 16

Table 2 shows an example of a number of symbols per slot, a number of slots per frame, and a number of slots per subframe based on the SCS, in a case where an extended CP is used.

TABLE 2 SCS (15*2^(u)) N^(slot) _(symb) N^(frame,u) _(slot) N^(subframe,u) _(slot) 60 KHz (u = 2) 12 40 4

In an NR system, OFDM(A) numerologies (e.g., SCS, CP length, and so on) between multiple cells being integrate to one UE may be differently configured. Accordingly, a (absolute time) duration (or section) of a time resource (e.g., subframe, slot or TTI) (collectively referred to as a time unit (TU) for simplicity) being configured of the same number of symbols may be differently configured in the integrated cells.

In the NR, multiple numerologies or SCSs for supporting diverse 5G services may be supported. For example, in case an SCS is 15 kHz, a wide area of the conventional cellular bands may be supported, and, in case an SCS is 30 kHz/60 kHz a dense-urban, lower latency, wider carrier bandwidth may be supported. In case the SCS is 60 kHz or higher, a bandwidth that is greater than 24.25 GHz may be used in order to overcome phase noise.

An NR frequency band may be defined as two different types of frequency ranges. The two different types of frequency ranges may be FR1 and FR2. The values of the frequency ranges may be changed (or varied), and, for example, the two different types of frequency ranges may be as shown below in Table 3. Among the frequency ranges that are used in an NR system, FR1 may mean a “sub 6 GHz range”, and FR2 may mean an “above 6 GHz range” and may also be referred to as a millimeter wave (mmW).

TABLE 3 Frequency Range Corresponding Subcarrier designation frequency range Spacing (SCS) FR1 450 MHz-6000 MHz 15, 30, 60 kHz FR2 24250 MHz-52600 MHz 60, 120, 240 kHz

As described above, the values of the frequency ranges in the NR system may be changed (or varied). For example, as shown below in Table 4, FR1 may include a band within a range of 410 MHz to 7125 MHz. More specifically, FR1 may include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, and so on) and higher. For example, a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, and so on) and higher being included in FR1 mat include an unlicensed band. The unlicensed band may be used for diverse purposes, e.g., the unlicensed band for vehicle-specific communication (e.g., automated driving).

TABLE 4 Frequency Range Corresponding Subcarrier designation frequency range Spacing (SCS) FR1 410 MHz-7125 MHz 15, 30, 60 kHz FR2 24250 MHz-52600 MHz 60, 120, 240 kHz

FIG. 4 shows a structure of a slot of an NR frame, based on an embodiment of the present disclosure. The embodiment of FIG. 4 may be combined with various embodiments of the present disclosure.

Referring to FIG. 4 , a slot includes a plurality of symbols in a time domain. For example, in case of a normal CP, one slot may include 14 symbols. However, in case of an extended CP, one slot may include 12 symbols. Alternatively, in case of a normal CP, one slot may include 7 symbols. However, in case of an extended CP, one slot may include 6 symbols.

A carrier includes a plurality of subcarriers in a frequency domain. A Resource Block (RB) may be defined as a plurality of consecutive subcarriers (e.g., 12 subcarriers) in the frequency domain. A Bandwidth Part (BWP) may be defined as a plurality of consecutive (Physical) Resource Blocks ((P)RBs) in the frequency domain, and the BWP may correspond to one numerology (e.g., SCS, CP length, and so on). A carrier may include a maximum of N number BWPs (e.g., 5 BWPs). Data communication may be performed via an activated BWP. Each element may be referred to as a Resource Element (RE) within a resource grid and one complex symbol may be mapped to each element.

Hereinafter, a bandwidth part (BWP) and a carrier will be described.

The BWP may be a set of consecutive physical resource blocks (PRBs) in a given numerology. The PRB may be selected from consecutive sub-sets of common resource blocks (CRBs) for the given numerology on a given carrier.

For example, the BWP may be at least any one of an active BWP, an initial BWP, and/or a default BWP. For example, the UE may not monitor downlink radio link quality in a DL BWP other than an active DL BWP on a primary cell (PCell). For example, the UE may not receive PDCCH, physical downlink shared channel (PDSCH), or channel state information—reference signal (CSI-RS) (excluding RRM) outside the active DL BWP. For example, the UE may not trigger a channel state information (CSI) report for the inactive DL BWP. For example, the UE may not transmit physical uplink control channel (PUCCH) or physical uplink shared channel (PUSCH) outside an active UL BWP. For example, in a downlink case, the initial BWP may be given as a consecutive RB set for a remaining minimum system information (RMSI) control resource set (CORESET) (configured by physical broadcast channel (PBCH)). For example, in an uplink case, the initial BWP may be given by system information block (SIB) for a random access procedure. For example, the default BWP may be configured by a higher layer. For example, an initial value of the default BWP may be an initial DL BWP. For energy saving, if the UE fails to detect downlink control information (DCI) during a specific period, the UE may switch the active BWP of the UE to the default BWP.

Meanwhile, the BWP may be defined for SL. The same SL BWP may be used in transmission and reception. For example, a transmitting UE may transmit a SL channel or a SL signal on a specific BWP, and a receiving UE may receive the SL channel or the SL signal on the specific BWP. In a licensed carrier, the SL BWP may be defined separately from a Uu BWP, and the SL BWP may have configuration signaling separate from the Uu BWP. For example, the UE may receive a configuration for the SL BWP from the BS/network. For example, the UE may receive a configuration for the Uu BWP from the BS/network. The SL BWP may be (pre-)configured in a carrier with respect to an out-of-coverage NR V2X UE and an RRC_IDLE UE. For the UE in the RRC_CONNECTED mode, at least one SL BWP may be activated in the carrier.

FIG. 5 shows an example of a BWP, based on an embodiment of the present disclosure. The embodiment of FIG. 5 may be combined with various embodiments of the present disclosure. It is assumed in the embodiment of FIG. 5 that the number of BWPs is 3.

Referring to FIG. 5 , a common resource block (CRB) may be a carrier resource block numbered from one end of a carrier band to the other end thereof. In addition, the PRB may be a resource block numbered within each BWP. A point A may indicate a common reference point for a resource block grid.

The BWP may be configured by a point A, an offset N^(start) _(BWP) from the point A, and a bandwidth N^(size) _(BWP). For example, the point A may be an external reference point of a PRB of a carrier in which a subcarrier 0 of all numerologies (e.g., all numerologies supported by a network on that carrier) is aligned. For example, the offset may be a PRB interval between a lowest subcarrier and the point A in a given numerology. For example, the bandwidth may be the number of PRBs in the given numerology.

Hereinafter, V2X or SL communication will be described.

A sidelink synchronization signal (SLSS) may include a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS), as a SL-specific sequence. The PSSS may be referred to as a sidelink primary synchronization signal (S-PSS), and the SSSS may be referred to as a sidelink secondary synchronization signal (S-SSS). For example, length-127 M-sequences may be used for the S-PSS, and length-127 gold sequences may be used for the S-SSS. For example, a UE may use the S-PSS for initial signal detection and for synchronization acquisition. For example, the UE may use the S-PSS and the S-SSS for acquisition of detailed synchronization and for detection of a synchronization signal ID.

A physical sidelink broadcast channel (PSBCH) may be a (broadcast) channel for transmitting default (system) information which must be first known by the UE before SL signal transmission/reception. For example, the default information may be information related to SLSS, a duplex mode (DM), a time division duplex (TDD) uplink/downlink (UL/DL) configuration, information related to a resource pool, a type of an application related to the SLSS, a subframe offset, broadcast information, or the like. For example, for evaluation of PSBCH performance, in NR V2X, a payload size of the PSBCH may be 56 bits including 24-bit cyclic redundancy check (CRC).

The S-PSS, the S-SSS, and the PSBCH may be included in a block format (e.g., SL synchronization signal (SS)/PSBCH block, hereinafter, sidelink-synchronization signal block (S-SSB)) supporting periodical transmission. The S-SSB may have the same numerology (i.e., SCS and CP length) as a physical sidelink control channel (PSCCH)/physical sidelink shared channel (PSSCH) in a carrier, and a transmission bandwidth may exist within a (pre-)configured sidelink (SL) BWP. For example, the S-SSB may have a bandwidth of 11 resource blocks (RBs). For example, the PSBCH may exist across 11 RBs. In addition, a frequency position of the S-SSB may be (pre-)configured. Accordingly, the UE does not have to perform hypothesis detection at frequency to discover the S-SSB in the carrier.

FIG. 6 shows a procedure of performing V2X or SL communication by a UE based on a transmission mode, based on an embodiment of the present disclosure. The embodiment of FIG. 6 may be combined with various embodiments of the present disclosure. In various embodiments of the present disclosure, the transmission mode may be called a mode or a resource allocation mode. Hereinafter, for convenience of explanation, in LTE, the transmission mode may be called an LTE transmission mode. In NR, the transmission mode may be called an NR resource allocation mode.

For example, (a) of FIG. 6 shows a UE operation related to an LTE transmission mode 1 or an LTE transmission mode 3. Alternatively, for example, (a) of FIG. 6 shows a UE operation related to an NR resource allocation mode 1. For example, the LTE transmission mode 1 may be applied to general SL communication, and the LTE transmission mode 3 may be applied to V2X communication.

For example, (b) of FIG. 6 shows a UE operation related to an LTE transmission mode 2 or an LTE transmission mode 4. Alternatively, for example, (b) of FIG. 6 shows a UE operation related to an NR resource allocation mode 2.

Referring to (a) of FIG. 6 , in the LTE transmission mode 1, the LTE transmission mode 3, or the NR resource allocation mode 1, a base station may schedule SL resource(s) to be used by a UE for SL transmission. For example, in step S600, a base station may transmit information related to SL resource(s) and/or information related to UL resource(s) to a first UE. For example, the UL resource(s) may include PUCCH resource(s) and/or PUSCH resource(s). For example, the UL resource(s) may be resource(s) for reporting SL HARQ feedback to the base station.

For example, the first UE may receive information related to dynamic grant (DG) resource(s) and/or information related to configured grant (CG) resource(s) from the base station. For example, the CG resource(s) may include CG type 1 resource(s) or CG type 2 resource(s). In the present disclosure, the DG resource(s) may be resource(s) configured/allocated by the base station to the first UE through a downlink control information (DCI). In the present disclosure, the CG resource(s) may be (periodic) resource(s) configured/allocated by the base station to the first UE through a DCI and/or an RRC message. For example, in the case of the CG type 1 resource(s), the base station may transmit an RRC message including information related to CG resource(s) to the first UE. For example, in the case of the CG type 2 resource(s), the base station may transmit an RRC message including information related to CG resource(s) to the first UE, and the base station may transmit a DCI related to activation or release of the CG resource(s) to the first UE.

In step S610, the first UE may transmit a PSCCH (e.g., sidelink control information (SCI) or 1^(st)-stage SCI) to a second UE based on the resource scheduling. In step S620, the first UE may transmit a PSSCH (e.g., 2^(nd)-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second UE. In step S630, the first UE may receive a PSFCH related to the PSCCH/PSSCH from the second UE. For example, HARQ feedback information (e.g., NACK information or ACK information) may be received from the second UE through the PSFCH. In step S640, the first UE may transmit/report HARQ feedback information to the base station through the PUCCH or the PUSCH. For example, the HARQ feedback information reported to the base station may be information generated by the first UE based on the HARQ feedback information received from the second UE. For example, the HARQ feedback information reported to the base station may be information generated by the first UE based on a pre-configured rule. For example, the DCI may be a DCI for SL scheduling. For example, a format of the DCI may be a DCI format 3_0 or a DCI format 3_1.

Hereinafter, an example of DCI format 3_0 will be described.

DCI format 3_0 is used for scheduling of NR PSCCH and NR PSSCH in one cell.

The following information is transmitted by means of the DCI format 3_0 with CRC scrambled by SL-RNTI or SL-CS-RNTI:

-   -   Resource pool index—ceiling (log₂ I) bits, where I is the number         of resource pools for transmission configured by the higher         layer parameter sl-TxPoolScheduling.     -   Time gap—3 bits determined by higher layer parameter         sl-DCI-ToSL-Trans     -   HARQ process number—4 bits     -   New data indicator—1 bit     -   Lowest index of the subchannel allocation to the initial         transmission—ceiling (log₂(N^(SL) _(subChannel))) bits     -   SCI format 1-A fields: frequency resource assignment, time         resource assignment     -   PSFCH-to-HARQ feedback timing indicator—ceiling (log₂         N_(fb_timing)) bits, where N_(fb_timing) is the number of         entries in the higher layer parameter sl-PSFCH-ToPUCCH.     -   PUCCH resource indicator—3 bits     -   Configuration index—0 bit if the UE is not configured to monitor         DCI format 3_0 with CRC scrambled by SL-CS-RNTI; otherwise 3         bits. If the UE is configured to monitor DCI format 3_0 with CRC         scrambled by SL-CS-RNTI, this field is reserved for DCI format         3_0 with CRC scrambled by SL-RNTI.     -   Counter sidelink assignment index—2 bits, 2 bits if the UE is         configured with pdsch-HARQ-ACK-Codebook=dynamic, 2 bits if the         UE is configured with pdsch-HARQ-ACK-Codebook=semi-static     -   Padding bits, if required

Referring to (b) of FIG. 6 , in the LTE transmission mode 2, the LTE transmission mode 4, or the NR resource allocation mode 2, a UE may determine SL transmission resource(s) within SL resource(s) configured by a base station/network or pre-configured SL resource(s). For example, the configured SL resource(s) or the pre-configured SL resource(s) may be a resource pool. For example, the UE may autonomously select or schedule resource(s) for SL transmission. For example, the UE may perform SL communication by autonomously selecting resource(s) within the configured resource pool. For example, the UE may autonomously select resource(s) within a selection window by performing a sensing procedure and a resource (re)selection procedure. For example, the sensing may be performed in a unit of subchannel(s). For example, in step S610, a first UE which has selected resource(s) from a resource pool by itself may transmit a PSCCH (e.g., sidelink control information (SCI) or 1^(st)-stage SCI) to a second UE by using the resource(s). In step S620, the first UE may transmit a PSSCH (e.g., 2^(nd)-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second UE. In step S630, the first UE may receive a PSFCH related to the PSCCH/PSSCH from the second UE.

Referring to (a) or (b) of FIG. 6 , for example, the first UE may transmit a SCI to the second UE through the PSCCH. Alternatively, for example, the first UE may transmit two consecutive SCIs (e.g., 2-stage SCI) to the second UE through the PSCCH and/or the PSSCH. In this case, the second UE may decode two consecutive SCIs (e.g., 2-stage SCI) to receive the PSSCH from the first UE. In the present disclosure, a SCI transmitted through a PSCCH may be referred to as a 1^(st) SCI, a first SCI, a 1^(st)-stage SCI or a 1^(st)-stage SCI format, and a SCI transmitted through a PSSCH may be referred to as a 2^(nd) SCI, a second SCI, a 2^(nd)-stage SCI or a 2^(nd)-stage SCI format. For example, the 1^(st)-stage SCI format may include a SCI format 1-A, and the 2^(nd)-stage SCI format may include a SCI format 2-A and/or a SCI format 2-B.

Hereinafter, an example of SCI format 1-A will be described.

SCI format 1-A is used for the scheduling of PSSCH and 2^(nd)-stage-SCI on PSSCH.

The following information is transmitted by means of the SCI format 1-A:

-   -   Priority—3 bits     -   Frequency resource assignment—ceiling (log₂ (N^(SL)         _(subChannel)(N^(SL) _(subChannel)+1)/2)) bits when the value of         the higher layer parameter sl-MaxNumPerReserve is configured to         2; otherwise ceiling log₂(N^(SL) _(subChannel)(N^(SL)         _(subChannel)+1)(2N^(SL) _(subChannel)+1)/6) bits when the value         of the higher layer parameter sl-MaxNumPerReserve is configured         to 3     -   Time resource assignment—5 bits when the value of the higher         layer parameter sl-MaxNumPerReserve is configured to 2;         otherwise 9 bits when the value of the higher layer parameter         sl-MaxNumPerReserve is configured to 3     -   Resource reservation period—ceiling (log₂ N_(rsvp_period)) bits,         where N_(rsv_period) is the number of entries in the higher         layer parameter sl-ResourceReservePeriodList, if higher layer         parameter sl-MultiReserveResource is configured; 0 bit otherwise     -   DMRS pattern—ceiling (log₂ N_(pattern)) bits, where N_(pattern)         is the number of DMRS patterns configured by higher layer         parameter sl-PSSCH-DMRS-TimePatternList     -   2^(nd)-stage SCI format—2 bits as defined in Table 5     -   Beta_offset indicator—2 bits as provided by higher layer         parameter sl-BetaOffsets2ndSCI     -   Number of DMRS port—1 bit as defined in Table 6     -   Modulation and coding scheme—5 bits     -   Additional MCS table indicator—1 bit if one MCS table is         configured by higher layer parameter sl-Additional-MCS-Table; 2         bits if two MCS tables are configured by higher layer parameter         sl-Additional-MCS-Table; 0 bit otherwise     -   PSFCH overhead indication—1 bit if higher layer parameter         sl-PSFCH-Period=2 or 4; 0 bit otherwise     -   Reserved—a number of bits as determined by higher layer         parameter sl-NumReservedBits, with value set to zero.

TABLE 5 Value of 2nd-stage SCI format field 2nd-stage SCI format 00 SCI format 2-A 01 SCI format 2-B 10 Reserved 11 Reserved

TABLE 6 Value of the Number of DMRS port field Antenna ports 0 1000 1 1000 and 1001

Hereinafter, an example of SCI format 2-A will be described.

SCI format 2-A is used for the decoding of PSSCH, with HARQ operation when HARQ-ACK information includes ACK or NACK, when HARQ-ACK information includes only NACK, or when there is no feedback of HARQ-ACK information.

The following information is transmitted by means of the SCI format 2-A:

-   -   HARQ process number—4 bits     -   New data indicator—1 bit     -   Redundancy version—2 bits     -   Source ID—8 bits     -   Destination ID—16 bits     -   HARQ feedback enabled/disabled indicator—1 bit     -   Cast type indicator—2 bits as defined in Table 7     -   CSI request—1 bit

TABLE 7 Value of Cast type indicator Cast type 00 Broadcast 01 Groupcast when HARQ-ACK information includes ACK or NACK 10 Unicast 11 Groupcast when HARQ-ACK information includes only NACK

Hereinafter, an example of SCI format 2-B will be described.

SCI format 2-B is used for the decoding of PSSCH, with HARQ operation when HARQ-ACK information includes only NACK, or when there is no feedback of HARQ-ACK information.

The following information is transmitted by means of the SCI format 2-B:

-   -   HARQ process number—4 bits     -   New data indicator—1 bit     -   Redundancy version—2 bits     -   Source ID—8 bits     -   Destination ID—16 bits     -   HARQ feedback enabled/disabled indicator—1 bit     -   Zone ID—12 bits     -   Communication range requirement—4 bits determined by higher         layer parameter sl-ZoneConfigMCR-Index

Referring to (a) or (b) of FIG. 6 , in step S630, the first UE may receive the PSFCH. For example, the first UE and the second UE may determine a PSFCH resource, and the second UE may transmit HARQ feedback to the first UE using the PSFCH resource.

Referring to (a) of FIG. 6 , in step S640, the first UE may transmit SL HARQ feedback to the base station through the PUCCH and/or the PUSCH.

FIG. 7 shows three cast types, based on an embodiment of the present disclosure. The embodiment of FIG. 7 may be combined with various embodiments of the present disclosure. Specifically, (a) of FIG. 7 shows broadcast-type SL communication, (b) of FIG. 7 shows unicast type-SL communication, and (c) of FIG. 7 shows groupcast-type SL communication. In case of the unicast-type SL communication, a UE may perform one-to-one communication with respect to another UE. In case of the groupcast-type SL transmission, the UE may perform SL communication with respect to one or more UEs in a group to which the UE belongs. In various embodiments of the present disclosure, SL groupcast communication may be replaced with SL multicast communication, SL one-to-many communication, or the like.

Hereinafter, a hybrid automatic repeat request (HARQ) procedure will be described.

For example, the SL HARQ feedback may be enabled for unicast. In this case, in a non-code block group (non-CBG) operation, if the receiving UE decodes a PSCCH of which a target is the receiving UE and if the receiving UE successfully decodes a transport block related to the PSCCH, the receiving UE may generate HARQ-ACK. In addition, the receiving UE may transmit the HARQ-ACK to the transmitting UE. Otherwise, if the receiving UE cannot successfully decode the transport block after decoding the PSCCH of which the target is the receiving UE, the receiving UE may generate the HARQ-NACK. In addition, the receiving UE may transmit HARQ-NACK to the transmitting UE.

For example, the SL HARQ feedback may be enabled for groupcast. For example, in the non-CBG operation, two HARQ feedback options may be supported for groupcast.

(1) Groupcast option 1: After the receiving UE decodes the PSCCH of which the target is the receiving UE, if the receiving UE fails in decoding of a transport block related to the PSCCH, the receiving UE may transmit HARQ-NACK to the transmitting UE through a PSFCH. Otherwise, if the receiving UE decodes the PSCCH of which the target is the receiving UE and if the receiving UE successfully decodes the transport block related to the PSCCH, the receiving UE may not transmit the HARQ-ACK to the transmitting UE.

(2) Groupcast option 2: After the receiving UE decodes the PSCCH of which the target is the receiving UE, if the receiving UE fails in decoding of the transport block related to the PSCCH, the receiving UE may transmit HARQ-NACK to the transmitting UE through the PSFCH. In addition, if the receiving UE decodes the PSCCH of which the target is the receiving UE and if the receiving UE successfully decodes the transport block related to the PSCCH, the receiving UE may transmit the HARQ-ACK to the transmitting UE through the PSFCH.

For example, if the groupcast option 1 is used in the SL HARQ feedback, all UEs performing groupcast communication may share a PSFCH resource. For example, UEs belonging to the same group may transmit HARQ feedback by using the same PSFCH resource.

For example, if the groupcast option 2 is used in the SL HARQ feedback, each UE performing groupcast communication may use a different PSFCH resource for HARQ feedback transmission. For example, UEs belonging to the same group may transmit HARQ feedback by using different PSFCH resources.

In the present disclosure, HARQ-ACK may be referred to as ACK, ACK information, or positive-ACK information, and HARQ-NACK may be referred to as NACK, NACK information, or negative-ACK information.

Hereinafter, UE procedure for reporting HARQ-ACK on sidelink will be described.

A UE can be indicated by an SCI format scheduling a PSSCH reception, in one or more sub-channels from a number of N^(PSSCH) _(subch) sub-channels, to transmit a PSFCH with HARQ-ACK information in response to the PSSCH reception. The UE provides HARQ-ACK information that includes ACK or NACK, or only NACK.

A UE can be provided, by sl-PSFCH-Period-r16, a number of slots in a resource pool for a period of PSFCH transmission occasion resources. If the number is zero, PSFCH transmissions from the UE in the resource pool are disabled. A UE expects that a slot t′_(k) ^(SL) (0≤k<T_(max)) has a PSFCH transmission occasion resource if k mod N^(PSFCH) _(PSSCH)=0, where t′_(k) ^(SL) is a slot that belongs to the resource pool, T′_(max) is a number of slots that belong to the resource pool within 10240 msec, and N^(PSFCH) _(PSSCH) is provided by sl-PSFCH-Period-r16. A UE may be indicated by higher layers to not transmit a PSFCH in response to a PSSCH reception. If a UE receives a PSSCH in a resource pool and the HARQ feedback enabled/disabled indicator field in an associated SCI format 2-A or a SCI format 2-B has value 1, the UE provides the HARQ-ACK information in a PSFCH transmission in the resource pool. The UE transmits the PSFCH in a first slot that includes PSFCH resources and is at least a number of slots, provided by sl-MinTimeGapPSFCH-r16, of the resource pool after a last slot of the PSSCH reception.

A UE is provided by sl-PSFCH-RB-Set-r16 a set of M^(PSFCH) _(PRB,set) PRBs in a resource pool for PSFCH transmission in a PRB of the resource pool. For a number of N_(subch) sub-channels for the resource pool, provided by sl-NumSubchannel, and a number of PSSCH slots associated with a PSFCH slot that is less than or equal to N^(PSFCH) _(PSSCH), the UE allocates the [(i+j·N^(PSFCH) _(PSSCH))·M^(PSFCH) _(subch,slot), (i+1+j·N^(PSFCH) _(PSSCH))·M^(PSFCH) _(subch,slot)−1] PRBs from the M_(PRB,set) ^(PSFCH) PRBs to slot i among the PSSCH slots associated with the PSFCH slot and sub-channel j, where M^(PSFCH) _(subch,slot)=M^(PSFCH) _(PRB,set)/(N_(subch)·N^(PSFCH) _(PSSCH)), 0≤i<N^(PSFCH) _(PSSCH), 0≤j<N_(subch), and the allocation starts in an ascending order of i and continues in an ascending order of j. The UE expects that M^(PSFCH) _(PRB,set) is a multiple of N_(subch)·N^(PSFCH) _(PSSCH).

A UE determines a number of PSFCH resources available for multiplexing HARQ-ACK information in a PSFCH transmission as R^(PSFCH) _(PRB,CS)=N^(PSFCH) _(type)·M^(PSFCH) _(subch,slot)·N^(PSFCH) _(CS) where N^(PSFCH) _(CS) is a number of cyclic shift pairs for the resource pool and, based on an indication by higher layers,

-   -   N^(PSFCH) _(type)=1 and the M^(PSFCH) _(subch,slot) PRBs are         associated with the starting sub-channel of the corresponding         PSSCH     -   N^(PSFCH) _(type)=N^(PSSCH) _(subch) and the N^(PSSCH)         _(subch)·M^(PSFCH) _(subch,slot) PRBs are associated with one or         more sub-channels from the N^(PSSCH) _(subch) sub-channels of         the corresponding PSSCH

The PSFCH resources are first indexed according to an ascending order of the PRB index, from the N^(PSFCH) _(type)·M^(PSFCH) _(subch,slot) PRBs, and then according to an ascending order of the cyclic shift pair index from the N^(PSFCH) _(CS) cyclic shift pairs.

A UE determines an index of a PSFCH resource for a PSFCH transmission in response to a PSSCH reception as (P_(ID)+M_(ID))_(mod) R^(PSFCH) _(PRB,CS) where P_(ID) is a physical layer source ID provided by SCI format 2-A or 2-B scheduling the PSSCH reception, and M_(ID) is the identity of the UE receiving the PSSCH as indicated by higher layers if the UE detects a SCI format 2-A with Cast type indicator field value of “01”; otherwise, M_(ID) is zero.

A UE determines a m₀ value, for computing a value of cyclic shift α, from a cyclic shift pair index corresponding to a PSFCH resource index and from N^(PSFCH) _(CS) using Table 8.

TABLE 8 m₀ cyclic shift cyclic shift cyclic shift cyclic shift cyclic shift cyclic shift N^(PSFCH) _(CS) pair index 0 pair index 1 pair index 2 pair index 3 pair index 4 pair index 5 1 0 — — — — — 2 0 3 — — — — 3 0 2 4 — — — 6 0 1 2 3 4 5

A UE determines a m_(cs) value, for computing a value or cyclic shift α, as in Table 9 if the UE detects a SCI format 2-A with Cast type indicator field value of “01” or “10”, or as in Table 10 if the UE detects a SCI format 2-B or a SCI format 2-A with Cast type indicator field value of “11”. The UE applies one cyclic shift from a cyclic shift pair to a sequence used for the PSFCH transmission.

TABLE 9 HARQ-ACK Value 0 (NACK) 1 (ACK) Sequence cyclic shift 0 6

TABLE 10 HARQ-ACK Value 0 (NACK) 1 (ACK) Sequence cyclic shift 0 N/A

Meanwhile, a power saving operation of the UE is not supported in NR V2X of release 16, and the power saving operation of the UE (e.g., Power Saving UE) will be supported from NR V2X of release 17.

For the power saving operation (e.g., sidelink DRX operation) of the UE, a sidelink DRX configuration (e.g., sidelink DRX cycle, sidelink DRX onduration, sidelink DRX offduration, timers for supporting the sidelink DRX operation, etc.) to be used by the Power Saving UE (P-UE) should be defined, and operations of the transmitting (TX) UE and the receiving (RX) UE in on-duration (e.g., duration where sidelink reception/transmission can be performed)/offduration (e.g., duration operating in sleep mode) should be defined.

FIG. 8 shows a method for an RX UE to perform a power saving operation based on SCI, based on an embodiment of the present disclosure. The embodiment of FIG. 8 may be combined with various embodiments of the present disclosure.

Referring to FIG. 8 , if the RX UE supporting a sidelink DRX operation receives SCI (SCI including reserved transmission scheduling information for PSSCH (i.e., sidelink data) reception) transmitted by the TX UE, the RX UE may monitor (or receive) a PSCCH/PSSCH transmitted by the TX UE by remaining an active state until the RX UE receives all PSCCH/PSSCH transmitted by the TX UE using the reserved transmission resource.

Meanwhile, the RX UE may perform a power saving operation based on resource reservation information (e.g., time resource assignment information and/or resource reservation period information) included in SCI transmitted by the TX UE. For example, the RX UE which has received SCI including information related to a second SL resource (i.e., the next retransmission resource) on a first SL resource may start a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer after the time domain of the first SL resource. In addition, the RX UE may stop the SL DRX HARQ RTT timer before the time domain of the second SL resource (i.e., the next retransmission resource). Through this, the RX UE can obtain a power saving gain. Meanwhile, even if SCI does not include information related to the second SL resource (i.e., the next retransmission resource), the RX UE needs to determine a value of the SL DRX HARQ RTT timer. Specifically, for example, since a SL DRX retransmission timer for monitoring retransmission by the TX UE is started after the SL DRX HARQ RTT timer expires, even if SCI does not include information related to the second SL resource (i.e., the next retransmission resource), the RX UE needs to determine the value of the SL DRX HARQ RTT timer to determine the start time of the SL DRX retransmission timer. If the rule for determining the value of the SL DRX HARQ RTT timer is not defined, the understanding of the value of the SL DRX HARQ RTT timer may be different between the TX UE and the RX UE, which may lead to a decrease in reliability of sidelink communication.

Based on various embodiments of the present disclosure, provided are a method for performing, by the RX UE which has received SCI (including reserved transmission resource information) and a PSSCH (e.g., SL data) associated with the SCI transmitted by the TX UE, a sidelink power saving operation based on reserved transmission resource information included in the SCI, and a device supporting the same. Based on various embodiments of the present disclosure, proposed are a method for obtaining, by the RX UE supporting a sidelink DRX operation, an additional power saving gain compared to the prior art, if the RX UE receives SCI (including reserved transmission schedule information) transmitted by the TX UE, and a device supporting the same.

FIG. 9 shows a procedure for an RX UE and/or a TX UE to perform SL communication based on a SL DRX configuration, based on an embodiment of the present disclosure. The embodiment of FIG. 9 may be combined with various embodiments of the present disclosure.

Referring to FIG. 9 , in step S910, the TX UE and/or the RX UE may obtain one or more DRX configurations. For example, the TX UE and/or the RX UE may receive the one or more DRX configurations from the base station. For example, the one or more DRX configurations may be configured or pre-configured for the TX UE and/or the RX UE. For example, the one or more DRX configurations may include Uu DRX configurations and/or SL DRX configurations.

For example, the Uu DRX configuration may include information related to drx-HARQ-RTT-Timer-SL and/or information related to drx-RetransmissionTimer-SL. For example, the timer may be used for the following purposes.

(1) drx-HARQ-RTT-Timer-SL (per HARQ process): drx-HARQ-RTT-Timer-SL may be the minimum duration before a sidelink HARQ retransmission grant is expected by the MAC entity. drx-HARQ-RTT-Timer-SL may refer to the minimum time required until a resource for SL mode 1 retransmission is prepared. That is, the resource for sidelink retransmission cannot be prepared before the drx-HARQ-RTT-Timer-SL timer. Accordingly, the TX UE can reduce power consumption by transitioning to a sleep mode during the drx-HARQ-RTT-Time-SL timer. Or, the TX UE may not perform mode 1 DCI monitoring from the base station. If the drx-HARQ-RTT-Timer-SL timer expires, the TX UE may determine that a resource for SL retransmission may be prepared. Accordingly, the TX UE may start the drx-RetransmissionTimer-SL timer and monitor whether resource(s) for SL HARQ retransmission is received. As soon as the drx-HARQ-RTT-Timer-SL timer expires, the SL HARQ retransmission resource(s) may or may not be received, so the TX UE may start the drx-RetransmissionTimer-SL timer, and the TX UE may monitor mode 1 DCI from the base station to receive resource(s) for SL HARQ retransmission. For example, the drx-HARQ-RTT-Timer-SL timer may be a duration in which the TX UE performing sidelink communication based on sidelink resource allocation mode 1 (e.g., the UE supporting Uu DRX operation) does not perform PDCCH (or DCI) monitoring for sidelink mode 1 resource allocation from the base station.

(2) drx-RetransmissionTimer-SL (per HARQ process): drx-RetransmissionTimer-SL may be the maximum duration until a grant for sidelink retransmission is received. That is, the drx-RetransmissionTimer-SL timer may be a timer started when the drx-HARQ-RTT-Timer-SL timer expires, and it may be a timer that allows the TX UE to transition to an active state for SL retransmission. Or, while the corresponding timer is running, the TX UE may monitor mode 1 DCI from the base station. The TX UE may start monitoring SL mode 1 DCI from the base station, in order to check whether retransmission resource(s) (i.e., grant for sidelink retransmission) to the RX UE is prepared, from a time when drx-RetransmissionTimer-SL starts. And, if retransmission resource(s) is prepared, the TX UE may perform sidelink HARQ retransmission to the RX UE. When transmitting a HARQ retransmission packet to the RX UE, the TX UE may stop the drx-RetransmissionTimer-SL timer. While the drx-RetransmissionTimer-SL timer is running, the UE may maintain an active state. For example, the drx-RetransmissionTimer-SL timer may be a duration in which the TX UE performing sidelink communication based on sidelink resource allocation mode 1 (e.g., the UE supporting Uu DRX operation) performs PDCCH (or DCI) monitoring for sidelink mode 1 resource allocation from the base station.

For example, the SL DRX configuration may include at least one parameter/information among parameters/information described below.

(1) SL drx-onDurationTimer: the duration at the beginning of a SL DRX Cycle

(2) SL drx-SlotOffset: the delay before starting the sl drx-onDurationTimer

(3) SL drx-InactivityTimer: the duration after the PSCCH occasion in which a PSCCH indicates a new SL transmission for the MAC entity

(4) SL drx-StartOffset: the subframe where the SL DRX cycle starts (the subframe where the SL DRX cycle start)

(5) SL drx-Cycle: SL DRX cycle

(6) SL drx-HARQ-RTT-Timer (per HARQ process or per sidelink process): the minimum duration before an assignment for HARQ retransmission is expected by the MAC entity the MAC entity)

(7) SL drx-RetransmissionTimer (per HARQ process or per sidelink process): the maximum duration until a retransmission is received

The SL DRX timer described in the present disclosure may be used for the following purposes.

(1) SL DRX onduration timer: the duration in which the UE performing the SL DRX operation should basically operate in an active time in order to receive a PSCCH/PSSCH from other UE(s)

(2) SL DRX inactivity timer: the duration extending the SL DRX onduration duration, which is the duration in which the UE performing the SL DRX operation should basically operate in the active time in order to receive the PSCCH/PSSCH from other UE(s)

For example, the UE may extend the SL DRX onduration timer by the SL DRX inactivity timer duration. In addition, if the UE receives a PSCCH (e.g., 1st SCI and 2^(nd) SCI) for a new transport block (TB) from other UE(s), or if the UE receives a new packet (e.g., new PSSCH transmission) from other UE(s), the UE may extend the SL DRX onduration timer by starting the SL DRX inactivity timer.

(3) SL DRX HARQ RTT timer: the duration in which the UE performing the SL DRX operation operates in a sleep mode until receiving a retransmission packet (or PSSCH assignment) transmitted by other UE(s)

For example, if the UE starts the SL DRX HARQ RTT timer, the UE may determine that other UE(s) will not transmit a sidelink retransmission packet to the UE until the SL DRX HARQ RTT timer expires, and the UE may operate in a sleep mode while the corresponding timer is running. For example, if the UE starts the SL DRX HARQ RTT timer, the UE may determine that the TX UE will not transmit a sidelink retransmission packet to the UE until the SL DRX HARQ RTT timer expires, and the UE may not monitor a sidelink channel/signal transmitted by the TX UE while the corresponding timer is running.

(4) SL DRX retransmission timer: the timer which starts when the SL DRX HARQ RTT timer expires, and the duration in which the UE performing the SL DRX operation operates in an active time in order to receive a retransmission packet (or PSSCH assignment) transmitted by other UE(s)

For example, for the corresponding timer duration, the UE may receive or monitor a retransmission sidelink packet (or PSSCH assignment) transmitted by other UE(s).

For example, the SL DRX configuration may include at least one of information related to a SL DRX timer, information related to a SL DRX slot offset, information related to a SL DRX start offset, and/or information related to a SL DRX cycle.

For example, the SL DRX timer may include at least one of a SL DRX onduration timer, a SL DRX inactivity timer, a SL DRX retransmission timer, and/or a SL DRX HARQ RTT timer. For example, the SL DRX onduration timer may be the duration at the beginning of an SL DRX cycle. For example, the SL DRX inactivity timer may be the duration after the first slot of SCI reception in which an SCI indicates a new SL transmission for the MAC entity. For example, the SL DRX retransmission timer may be the maximum duration until an SL retransmission is received. For example, the SL DRX HARQ RTT timer may be the minimum duration before an SL HARQ retransmission is expected by the MAC entity. For example, the SL DRX retransmission timer and the SL DRX HARQ RTT timer may be configured per sidelink process. For example, the SL DRX inactivity timer, the SL DRX retransmission timer, and the SL DRX HARQ RTT timer may not be applied to broadcast transmission. For example, the UE may start the SL DRX retransmission timer after the SL DRX HARQ RTT timer expires.

For example, the SL DRX slot offset may be a delay before the start of the SL DRX onduration timer. For example, the SL DRX start offset may be the slot where the SL DRX cycle starts.

For example, a time while at least one of the SL DRX onduration timer, the SL DRX inactivity timer, and/or the SL DRX retransmission timer is running may be an active time. However, in various embodiments of the present disclosure, the active time is not limited to the time while at least one of the SL DRX onduration timer, the SL DRX inactivity timer, and/or the SL DRX retransmission timer is running. For example, even if the SL DRX onduration timer, the SL DRX inactivity timer, and the SL DRX retransmission timer are not running, the RX UE may operate in an active time, and the RX UE may monitor a PSCCH from the TX UE.

In the present disclosure, the names of the timer (Uu DRX HARQ RTT TimerSL, Uu DRX Retransmission TimerSL, Sidelink DRX Onduration Timer, Sidelink DRX Inactivity Timer, Sidelink DRX HARQ RTT Timer, Sidelink DRX Retransmission Timer, drx-HARQ-RTT-TimerSL, drx-RetransmissionTimerSL, etc.) is exemplary, and a timer performing the same/similar function based on the contents described in each timer may be considered as the same/similar timer regardless of the names of the timer.

In step S920, the RX UE may receive SCI from the TX UE. For example, the RX UE may receive SCI from the TX UE through a PSCCH. For example, the SCI may include time resource assignment information. For example, the time resource assignment information may include information related to a resource for current PSSCH transmission and reception. For example, the time resource assignment information may include information related to a resource for current PSSCH transmission and reception and information related to a resource for next PSSCH transmission and reception (i.e., retransmission resource).

In step S930, the RX UE may receive data from the TX UE. For example, the RX UE may receive data from the TX UE through a PSSCH.

In step S940, the RX UE and/or the TX UE may determine a value of the SL DRX HARQ RTT timer. In step S950, the RX UE may start the SL DRX HARQ RTT timer. In addition, based on the expiration of the SL DRX HARQ RTT timer, the RX UE may start the SL DRX retransmission timer. Through this, the RX UE can obtain an additional power saving gain. Hereinafter, a method for determining the value of the SL DRX HARQ RTT timer by the RX UE and/or the TX UE will be described in detail.

Based on an embodiment of the present disclosure, the RX UE may check information (i.e., reserved transmission scheduling information) included in SCI transmitted by the TX UE, and the RX UE may perform a power saving operation by transitioning to a sidelink sleep mode before reaching the scheduled transmission time. Or, the RX UE may configure the value of the SL DRX HARQ RTT timer based on reserved transmission scheduling information included in the SCI.

FIG. 10 shows a method for performing a power saving operation based on resource reservation information included in SCI, based on an embodiment of the present disclosure. The embodiment of FIG. 10 may be combined with various embodiments of the present disclosure.

Referring to FIG. 10 , the TX UE may select/reserve resources for up to three transmissions through SCI, and the TX UE may inform the RX UE of information regarding the resources through the SCI. The RX UE may check transmission scheduling information (i.e., resource scheduling information selected/reserved by the TX UE) included in the SCI transmitted by the TX UE, and the RX UE may infer the time of three transmissions (1⁴ PSSCH transmission, 2^(nd) PSSCH transmission, 3rd PSSCH transmission) to be performed by the TX UE. Therefore, as in the embodiment of FIG. 10 , the RX UE may perform a power saving operation by transitioning to a sidelink sleep mode (or configuring the value of the SL DRX HARQ RTT timer) from the time when the RX UE completes reception of the 1st transmission to the time when the RX UE receives the 2^(nd) transmission. In addition, the RX UE may perform the power saving operation by transitioning to the sidelink sleep mode from the time when the RX UE completes reception of the 2^(nd) transmission to the time when the RX UE receives the 3rd transmission.

For example, if the RX UE receives SCI and the received SCI does not include resource information for next transmission, the RX UE may perform a sleep operation. As in the embodiment of FIG. 10 , if the RX UE receives SCI at the location of the 3rd transmission and the received SCI does not include resource information for next transmission, the RX UE may set the value of the SL HARQ RTT timer as 0. In this case, the RX UE may immediately start the SL DRX retransmission timer and operate in an active time.

Based on an embodiment of the present disclosure, if the RX UE receives SCI, the RX UE may perform monitoring for SCI reception in a resource reservation period information included in the received SCI. In this case, the RX UE may fail to receive SCI. For example, if the TX UE fails to perform PSCCH/PSSCH transmission due to pre-emption, re-evaluation, UL-SL prioritization, NR SL-LTE SL prioritization, congestion control, etc., the RX UE may fail to receive SCI in the reserved resource period. Therefore, in this case (in case that the RX UE fails to receive SCI in the reserved resource period confirmed through the previous SCI), the RX UE may perform the SL DRX operation by setting the value of the SL HARQ RTT timer to 0. That is, the RX UE may immediately start the SL DRX retransmission timer and operate in an active time.

Based on an embodiment of the present disclosure, the base station may instruct the UE to set the value of the SL HARQ RTT timer based on resource reservation information indicated by SCI. For example, the base station may instruct the UE to set the value of the SL HARQ RTT timer based on resource reservation information indicated by SCI through an RRC message. In addition, the base station may instruct the UE to set the value of the SL HARQ RTT timer to a value of 0 rather than a value set based on resource reservation information indicated by SCI. For example, the base station may instruct the UE through an RRC message to set the value of the SL HARQ RTT timer to a value of 0 rather than a value set based on resource reservation information indicated by SCI. That is, based on the option indicated by the base station (option 1: setting the value of the SL DRX HARQ RTT timer based on SCI, option 2: setting the value of the SL HARQ RTT timer to 0), the UE may select whether to apply the value of the SL HARQ RTT timer configured based on resource reservation information indicated by SCI or the value of the SL HARQ RTT timer configured as 0.

The embodiments of the present disclosure can be equally applied to a SL active time period (duration in which the UE monitors sidelink channels or signals) and a SL inactive time period (duration in which the UE does not need to monitor sidelink channels or signals, and/or duration in which the UE can operate in a power saving mode). Or, the embodiments of the present disclosure can be applied even when the UE receives SCI from other UE(s) at the end of the SL active time and the next transmission resource reserved through the received SCI at the active time is in the SL inactive time period.

The proposal of the present disclosure can be applied/extended to/as a method of solving a problem in which loss occurs due to interruption which occurs during Uu BWP switching. In addition, in the case of a plurality of SL BWPs being supported for the UE, the proposal of the present disclosure can be applied/extended to/as a method of solving a problem in which loss occurs due to interruption which occurs during SL BWP switching.

The proposal of the present disclosure can be applied/extended to/as UE-pair specific SL DRX configuration(s), UE-pair specific SL DRX pattern(s) or parameter(s) (e.g., timer) included in UE-pair specific SL DRX configuration(s), as well as default/common SL DRX configuration(s), default/common SL DRX pattern(s), or parameter(s) (e.g., timer) included in default/common SL DRX configuration(s). In addition, the on-duration mentioned in the proposal of the present disclosure may be extended to or interpreted as an active time (e.g., time to wake-up state (e.g., RF module turned on) to receive/transmit radio signal(s)) duration, and the off-duration may be extended to or interpreted as a sleep time (e.g., time to sleep in sleep mode state (e.g., RF module turned off) to save power) duration. It does not mean that the TX UE is obligated to operate in the sleep mode in the sleep time duration. If necessary, the TX UE may be allowed to operate in an active time for a while for a sensing operation and/or a transmission operation, even if it is a sleep time.

For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each resource pool. For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each congestion level. For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each service priority. For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each service type. For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each resource pool. For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each QoS requirement (e.g., latency, reliability). For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each PQI (5G QoS identifier (5QI) for PC5). For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each traffic type (e.g., periodic generation or aperiodic generation). For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each SL transmission resource allocation mode (e.g., mode 1 or mode 2). For example, whether or not the (some) proposed method/rule of the present disclosure is applied and/or related parameter(s) (e.g., threshold value(s)) may be configured (differently or independently) for each Tx profile (e.g., a Tx profile indicating that a service supports a sidelink DRX operation, and a Tx profile indicating that a service does not need to support a sidelink DRX operation).

For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each resource pool (e.g., resource pool in which PSFCH is configured, resource pool in which PSFCH is not configured). For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each service/packet type. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each service/packet priority. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each QoS profile or for each QoS requirement (e.g., URLLC/EMBB traffic, reliability, latency). For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each PQI. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each PFI. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each cast type (e.g., unicast, groupcast, broadcast). For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each (resource pool) congestion level (e.g., CBR). For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each SL HARQ feedback option (e.g., NACK-only feedback, ACK/NACK feedback). For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for HARQ Feedback Enabled MAC PDU transmission. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for HARQ Feedback Disabled MAC PDU transmission. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) according to whether a PUCCH-based SL HARQ feedback reporting operation is configured or not. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for whether pre-emption is performed. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for pre-emption-based resource reselection. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for whether re-evaluation is performed. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for re-evaluation-based resource reselection. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each (L2 or L1) (source and/or destination) identifier. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each (L2 or L1) (a combination of source ID and destination ID) identifier. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each (L2 or L1) (a combination of a pair of source ID and destination ID and a cast type) identifier. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each direction of a pair of source layer ID and destination layer ID. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each PC5 RRC connection/link. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for the case of performing SL DRX. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for the case of not performing SL DRX. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for the case of supporting SL DRX. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for the case of not supporting SL DRX. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured (differently or independently) for each SL mode type (e.g., resource allocation mode 1 or resource allocation mode 2). For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for the case of performing (a) periodic resource reservation. For example, whether or not the proposed rule of the present disclosure is applied and/or related parameter configuration value(s) may be configured specifically (or differently or independently) for each Tx profile (e.g., a Tx profile indicating that a service supports a sidelink DRX operation, and a Tx profile indicating that a service does not need to support a sidelink DRX operation).

The certain time mentioned in the proposal of the present disclosure may refer to a time during which a UE operates in an active time for a pre-defined time in order to receive sidelink signal(s) or sidelink data from a counterpart UE. The certain time mentioned in the proposal of the present disclosure may refer to a time during which a UE operates in an active time as long as a specific timer (e.g., sidelink DRX retransmission timer, sidelink DRX inactivity timer, or timer to ensure that an RX UE can operate in an active time in a DRX operation of the RX UE) is running in order to receive sidelink signal(s) or sidelink data from a counterpart UE. In addition, the proposal and whether or not the proposal rule of the present disclosure is applied (and/or related parameter configuration value(s)) may also be applied to a mmWave SL operation.

Based on various embodiments of the present disclosure, if SCI transmitted by the TX UE does not include information related to the next retransmission resource, the RX UE may determine the value of the SL DRX HARQ RTT timer as 0. Through this, it is possible to lower the probability that the RX UE fails to receive retransmission by the TX UE, and reliability of SL communication between the TX UE and the RX UE can be guaranteed. Furthermore, if SCI transmitted by the TX UE does not include information related to the next retransmission resource, the TX UE may determine/consider that the RX UE sets the value of the SL DRX HARQ RTT timer to 0. Therefore, the TX UE can reserve SL resources or be allocated SL resources within the earliest possible time, and the TX UE may perform retransmission to the RX UE based on the SL resources. Through this, the latency of SL communication can be reduced, and reliability of SL communication between the TX UE and the RX UE can be guaranteed.

FIG. 11 shows a method for performing wireless communication by a first device, based on an embodiment of the present disclosure. The embodiment of FIG. 11 may be combined with various embodiments of the present disclosure.

Referring to FIG. 11 , in step S1110, the first device may obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer. In step S1120, the first device may receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH). In step S1130, the first device may receive, from the second device through the PSSCH, the second SCI and data. In step S1140, the first device may determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI. In step S1150, the first device may start the SL DRX retransmission timer.

For example, the value of the SL DRX HARQ RTT timer may represent a minimum duration before SL HARQ retransmission is expected by the first device.

For example, the value of the SL DRX retransmission timer may represent a maximum duration until SL retransmission is received.

For example, the value of the SL DRX retransmission timer and the value of the SL DRX HARQ RTT timer may be configured per SL process.

Additionally, for example, the first device may start the SL DRX HARQ RTT timer in a slot following an end of reception of the PSSCH. For example, the SL DRX retransmission timer may be started based on expiration of the SL DRX HARQ RTT timer.

For example, based on that (i) the information related to the next retransmission resource is not included in the first SCI and (ii) a physical sidelink feedback channel (PSFCH) resource is not configured, the value of the SL DRX HARQ RTT timer may be determined as zero.

For example, the first SCI may include information related to time resource assignment, and the information related to the time resource assignment may include only time information for the PSSCH.

Additionally, for example, the first device may receive, from a base station, information for determining the value of the SL DRX HARQ RTT timer as zero. For example, based on (i) the first SCI not including the information related to the next retransmission resource and (ii) the information for determining the value of the SL DRX HARQ RTT timer as zero, the value of the SL DRX HARQ RTT timer may be determined as zero. For example, the information for determining the value of the SL DRX HARQ RTT timer as zero may be information related to a SL resource pool for which a PSFCH is not configured. For example, the information for determining the value of the SL DRX HARQ RTT timer as zero may be received from the base station through a radio resource control (RRC) message.

For example, a time during which the SL DRX retransmission timer is running may be an active time of the first device.

The proposed method can be applied to the device(s) based on various embodiments of the present disclosure. First, the processor 102 of the first device 100 may obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer. In addition, the processor 102 of the first device 100 may control the transceiver 106 to receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH). In addition, the processor 102 of the first device 100 may control the transceiver 106 to receive, from the second device through the PSSCH, the second SCI and data. In addition, the processor 102 of the first device 100 may determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI. In addition, the processor 102 of the first device 100 may start the SL DRX retransmission timer.

Based on an embodiment of the present disclosure, a first device adapted to perform wireless communication may be provided. For example, the first device may comprise: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers. For example, the one or more processors may execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; control the one or more transceivers to receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); control the one or more transceivers to receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.

Based on an embodiment of the present disclosure, a processing device adapted to control a first device may be provided. For example, the processing device may comprise: one or more processors; and one or more memories operably connected to the one or more processors and storing instructions. For example, the one or more processors may execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.

Based on an embodiment of the present disclosure, a non-transitory computer readable storage medium storing instructions may be provided. For example, the instructions, when executed, may cause a first device to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.

FIG. 12 shows a method for performing wireless communication by a second device, based on an embodiment of the present disclosure. The embodiment of FIG. 12 may be combined with various embodiments of the present disclosure.

Referring to FIG. 12 , in step S1210, the second device may obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer. In step S1220, the second device may transmit, to a first device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH). In step S1230, the second device may transmit, to the first device through the PSSCH, the second SCI and data. In step S1240, the second device may determine, based on that information related to a next retransmission resource is not included in the first SCI, that the first device sets a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer to zero.

The proposed method can be applied to the device(s) based on various embodiments of the present disclosure. First, the processor 202 of the second device 200 may obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer. In addition, the processor 202 of the second device 200 may control the transceiver 206 to transmit, to a first device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH). In addition, the processor 202 of the second device 200 may control the transceiver 206 to transmit, to the first device through the PSSCH, the second SCI and data. In addition, the processor 202 of the second device 200 may determine, based on that information related to a next retransmission resource is not included in the first SCI, that the first device sets a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer to zero.

Based on an embodiment of the present disclosure, a second device adapted to perform wireless communication may be provided. For example, the second device may comprise: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers. For example, the one or more processors may execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; control the one or more transceivers to transmit, to a first device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); control the one or more transceivers to transmit, to the first device through the PSSCH, the second SCI and data; and determine, based on that information related to a next retransmission resource is not included in the first SCI, that the first device sets a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer to zero.

Based on an embodiment of the present disclosure, a processing device adapted to control a second device may be provided. For example, the processing device may comprise: one or more processors; and one or more memories operably connected to the one or more processors and storing instructions. For example, the one or more processors may execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; transmit, to a first device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); transmit, to the first device through the PSSCH, the second SCI and data; and determine, based on that information related to a next retransmission resource is not included in the first SCI, that the first device sets a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer to zero.

Based on an embodiment of the present disclosure, a non-transitory computer readable storage medium storing instructions may be provided. For example, the instructions, when executed, may cause a second device to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; transmit, to a first device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); transmit, to the first device through the PSSCH, the second SCI and data; and determine, based on that information related to a next retransmission resource is not included in the first SCI, that the first device sets a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer to zero.

Various embodiments of the present disclosure may be combined with each other.

Hereinafter, device(s) to which various embodiments of the present disclosure can be applied will be described.

The various descriptions, functions, procedures, proposals, methods, and/or operational flowcharts of the present disclosure described in this document may be applied to, without being limited to, a variety of fields requiring wireless communication/connection (e.g., 5G) between devices.

Hereinafter, a description will be given in more detail with reference to the drawings. In the following drawings/description, the same reference symbols may denote the same or corresponding hardware blocks, software blocks, or functional blocks unless described otherwise.

FIG. 13 shows a communication system 1, based on an embodiment of the present disclosure. The embodiment of FIG. 13 may be combined with various embodiments of the present disclosure.

Referring to FIG. 13 , a communication system 1 to which various embodiments of the present disclosure are applied includes wireless devices, Base Stations (BSs), and a network. Herein, the wireless devices represent devices performing communication using Radio Access Technology (RAT) (e.g., 5G New RAT (NR)) or Long-Term Evolution (LTE)) and may be referred to as communication/radio/5G devices. The wireless devices may include, without being limited to, a robot 100 a, vehicles 100 b-1 and 100 b-2, an eXtended Reality (XR) device 100 c, a hand-held device 100 d, a home appliance 100 e, an Internet of Things (IoT) device 100 f, and an Artificial Intelligence (AI) device/server 400. For example, the vehicles may include a vehicle having a wireless communication function, an autonomous vehicle, and a vehicle capable of performing communication between vehicles. Herein, the vehicles may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). The XR device may include an Augmented Reality (AR)/Virtual Reality (VR)/Mixed Reality (MR) device and may be implemented in the form of a Head-Mounted Device (HMD), a Head-Up Display (HUD) mounted in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance device, a digital signage, a vehicle, a robot, etc. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), and a computer (e.g., a notebook). The home appliance may include a TV, a refrigerator, and a washing machine. The IoT device may include a sensor and a smartmeter. For example, the BSs and the network may be implemented as wireless devices and a specific wireless device 200 a may operate as a BS/network node with respect to other wireless devices.

Here, wireless communication technology implemented in wireless devices 100 a to 100 f of the present disclosure may include Narrowband Internet of Things for low-power communication in addition to LTE, NR, and 6G. In this case, for example, NB-IoT technology may be an example of Low Power Wide Area Network (LPWAN) technology and may be implemented as standards such as LTE Cat NB1, and/or LTE Cat NB2, and is not limited to the name described above. Additionally or alternatively, the wireless communication technology implemented in the wireless devices 100 a to 100 f of the present disclosure may perform communication based on LTE-M technology. In this case, as an example, the LTE-M technology may be an example of the LPWAN and may be called by various names including enhanced Machine Type Communication (eMTC), and the like. For example, the LTE-M technology may be implemented as at least any one of various standards such as 1) LTE CAT 0, 2) LTE Cat M1, 3) LTE Cat M2, 4) LTE non-Bandwidth Limited (non-BL), 5) LTE-MTC, 6) LTE Machine Type Communication, and/or 7) LTE M, and is not limited to the name described above. Additionally or alternatively, the wireless communication technology implemented in the wireless devices 100 a to 100 f of the present disclosure may include at least one of Bluetooth, Low Power Wide Area Network (LPWAN), and ZigBee considering the low-power communication, and is not limited to the name described above. As an example, the ZigBee technology may generate personal area networks (PAN) related to small/low-power digital communication based on various standards including IEEE 802.15.4, and the like, and may be called by various names.

The wireless devices 100 a to 100 f may be connected to the network 300 via the BSs 200. An AI technology may be applied to the wireless devices 100 a to 100 f and the wireless devices 100 a to 100 f may be connected to the AI server 400 via the network 300. The network 300 may be configured using a 3G network, a 4G (e.g., LTE) network, or a 5G (e.g., NR) network. Although the wireless devices 100 a to 100 f may communicate with each other through the BSs 200/network 300, the wireless devices 100 a to 100 f may perform direct communication (e.g., sidelink communication) with each other without passing through the BSs/network. For example, the vehicles 100 b-1 and 100 b-2 may perform direct communication (e.g. Vehicle-to-Vehicle (V2V)/Vehicle-to-everything (V2X) communication). The IoT device (e.g., a sensor) may perform direct communication with other IoT devices (e.g., sensors) or other wireless devices 100 a to 100 f.

Wireless communication/connections 150 a, 150 b, or 150 c may be established between the wireless devices 100 a to 100 f/BS 200, or BS 200/BS 200. Herein, the wireless communication/connections may be established through various RATs (e.g., 5G NR) such as uplink/downlink communication 150 a, sidelink communication 150 b (or, D2D communication), or inter BS communication (e.g. relay, Integrated Access Backhaul (TAB)). The wireless devices and the BSs/the wireless devices may transmit/receive radio signals to/from each other through the wireless communication/connections 150 a and 150 b. For example, the wireless communication/connections 150 a and 150 b may transmit/receive signals through various physical channels. To this end, at least a part of various configuration information configuring processes, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, and resource mapping/demapping), and resource allocating processes, for transmitting/receiving radio signals, may be performed based on the various proposals of the present disclosure.

FIG. 14 shows wireless devices, based on an embodiment of the present disclosure. The embodiment of FIG. 14 may be combined with various embodiments of the present disclosure.

Referring to FIG. 14 , a first wireless device 100 and a second wireless device 200 may transmit radio signals through a variety of RATs (e.g., LTE and NR). Herein, {the first wireless device 100 and the second wireless device 200} may correspond to {the wireless device 100 x and the BS 200} and/or {the wireless device 100 x and the wireless device 100 x} of FIG. 13 .

The first wireless device 100 may include one or more processors 102 and one or more memories 104 and additionally further include one or more transceivers 106 and/or one or more antennas 108. The processor(s) 102 may control the memory(s) 104 and/or the transceiver(s) 106 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s) 102 may process information within the memory(s) 104 to generate first information/signals and then transmit radio signals including the first information/signals through the transceiver(s) 106. The processor(s) 102 may receive radio signals including second information/signals through the transceiver 106 and then store information obtained by processing the second information/signals in the memory(s) 104. The memory(s) 104 may be connected to the processor(s) 102 and may store a variety of information related to operations of the processor(s) 102. For example, the memory(s) 104 may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) 102 or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s) 102 and the memory(s) 104 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 106 may be connected to the processor(s) 102 and transmit and/or receive radio signals through one or more antennas 108. Each of the transceiver(s) 106 may include a transmitter and/or a receiver. The transceiver(s) 106 may be interchangeably used with Radio Frequency (RF) unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip.

The second wireless device 200 may include one or more processors 202 and one or more memories 204 and additionally further include one or more transceivers 206 and/or one or more antennas 208. The processor(s) 202 may control the memory(s) 204 and/or the transceiver(s) 206 and may be configured to implement the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. For example, the processor(s) 202 may process information within the memory(s) 204 to generate third information/signals and then transmit radio signals including the third information/signals through the transceiver(s) 206. The processor(s) 202 may receive radio signals including fourth information/signals through the transceiver(s) 106 and then store information obtained by processing the fourth information/signals in the memory(s) 204. The memory(s) 204 may be connected to the processor(s) 202 and may store a variety of information related to operations of the processor(s) 202. For example, the memory(s) 204 may store software code including commands for performing a part or the entirety of processes controlled by the processor(s) 202 or for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Herein, the processor(s) 202 and the memory(s) 204 may be a part of a communication modem/circuit/chip designed to implement RAT (e.g., LTE or NR). The transceiver(s) 206 may be connected to the processor(s) 202 and transmit and/or receive radio signals through one or more antennas 208. Each of the transceiver(s) 206 may include a transmitter and/or a receiver. The transceiver(s) 206 may be interchangeably used with RF unit(s). In the present disclosure, the wireless device may represent a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless devices 100 and 200 will be described more specifically. One or more protocol layers may be implemented by, without being limited to, one or more processors 102 and 202. For example, the one or more processors 102 and 202 may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, and SDAP). The one or more processors 102 and 202 may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Unit (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors 102 and 202 may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. The one or more processors 102 and 202 may generate signals (e.g., baseband signals) including PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document and provide the generated signals to the one or more transceivers 106 and 206. The one or more processors 102 and 202 may receive the signals (e.g., baseband signals) from the one or more transceivers 106 and 206 and acquire the PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document.

The one or more processors 102 and 202 may be referred to as controllers, microcontrollers, microprocessors, or microcomputers. The one or more processors 102 and 202 may be implemented by hardware, firmware, software, or a combination thereof. As an example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software and the firmware or software may be configured to include the modules, procedures, or functions. Firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be included in the one or more processors 102 and 202 or stored in the one or more memories 104 and 204 so as to be driven by the one or more processors 102 and 202. The descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of code, commands, and/or a set of commands.

The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 and store various types of data, signals, messages, information, programs, code, instructions, and/or commands. The one or more memories 104 and 204 may be configured by Read-Only Memories (ROMs), Random Access Memories (RAMs), Electrically Erasable Programmable Read-Only Memories (EPROMs), flash memories, hard drives, registers, cash memories, computer-readable storage media, and/or combinations thereof. The one or more memories 104 and 204 may be located at the interior and/or exterior of the one or more processors 102 and 202. The one or more memories 104 and 204 may be connected to the one or more processors 102 and 202 through various technologies such as wired or wireless connection.

The one or more transceivers 106 and 206 may transmit user data, control information, and/or radio signals/channels, mentioned in the methods and/or operational flowcharts of this document, to one or more other devices. The one or more transceivers 106 and 206 may receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, from one or more other devices. For example, the one or more transceivers 106 and 206 may be connected to the one or more processors 102 and 202 and transmit and receive radio signals. For example, the one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may transmit user data, control information, or radio signals to one or more other devices. The one or more processors 102 and 202 may perform control so that the one or more transceivers 106 and 206 may receive user data, control information, or radio signals from one or more other devices. The one or more transceivers 106 and 206 may be connected to the one or more antennas 108 and 208 and the one or more transceivers 106 and 206 may be configured to transmit and receive user data, control information, and/or radio signals/channels, mentioned in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document, through the one or more antennas 108 and 208. In this document, the one or more antennas may be a plurality of physical antennas or a plurality of logical antennas (e.g., antenna ports).

The one or more transceivers 106 and 206 may convert received radio signals/channels etc. from RF band signals into baseband signals in order to process received user data, control information, radio signals/channels, etc. using the one or more processors 102 and 202. The one or more transceivers 106 and 206 may convert the user data, control information, radio signals/channels, etc. processed using the one or more processors 102 and 202 from the base band signals into the RF band signals. To this end, the one or more transceivers 106 and 206 may include (analog) oscillators and/or filters.

FIG. 15 shows a signal process circuit for a transmission signal, based on an embodiment of the present disclosure. The embodiment of FIG. 15 may be combined with various embodiments of the present disclosure.

Referring to FIG. 15 , a signal processing circuit 1000 may include scramblers 1010, modulators 1020, a layer mapper 1030, a precoder 1040, resource mappers 1050, and signal generators 1060. An operation/function of FIG. 15 may be performed, without being limited to, the processors 102 and 202 and/or the transceivers 106 and 206 of FIG. 14 . Hardware elements of FIG. 15 may be implemented by the processors 102 and 202 and/or the transceivers 106 and 206 of FIG. 14 . For example, blocks 1010 to 1060 may be implemented by the processors 102 and 202 of FIG. 14 . Alternatively, the blocks 1010 to 1050 may be implemented by the processors 102 and 202 of FIG. 14 and the block 1060 may be implemented by the transceivers 106 and 206 of FIG. 14 .

Codewords may be converted into radio signals via the signal processing circuit 1000 of FIG. 15 . Herein, the codewords are encoded bit sequences of information blocks. The information blocks may include transport blocks (e.g., a UL-SCH transport block, a DL-SCH transport block). The radio signals may be transmitted through various physical channels (e.g., a PUSCH and a PDSCH).

Specifically, the codewords may be converted into scrambled bit sequences by the scramblers 1010. Scramble sequences used for scrambling may be generated based on an initialization value, and the initialization value may include ID information of a wireless device. The scrambled bit sequences may be modulated to modulation symbol sequences by the modulators 1020. A modulation scheme may include pi/2-Binary Phase Shift Keying (pi/2-BPSK), m-Phase Shift Keying (m-PSK), and m-Quadrature Amplitude Modulation (m-QAM). Complex modulation symbol sequences may be mapped to one or more transport layers by the layer mapper 1030. Modulation symbols of each transport layer may be mapped (precoded) to corresponding antenna port(s) by the precoder 1040. Outputs z of the precoder 1040 may be obtained by multiplying outputs y of the layer mapper 1030 by an N*M precoding matrix W.

Herein, N is the number of antenna ports and M is the number of transport layers. The precoder 1040 may perform precoding after performing transform precoding (e.g., DFT) for complex modulation symbols. Alternatively, the precoder 1040 may perform precoding without performing transform precoding.

The resource mappers 1050 may map modulation symbols of each antenna port to time-frequency resources. The time-frequency resources may include a plurality of symbols (e.g., a CP-OFDMA symbols and DFT-s-OFDMA symbols) in the time domain and a plurality of subcarriers in the frequency domain. The signal generators 1060 may generate radio signals from the mapped modulation symbols and the generated radio signals may be transmitted to other devices through each antenna. For this purpose, the signal generators 1060 may include Inverse Fast Fourier Transform (IFFT) modules, Cyclic Prefix (CP) inserters, Digital-to-Analog Converters (DACs), and frequency up-converters.

Signal processing procedures for a signal received in the wireless device may be configured in a reverse manner of the signal processing procedures 1010 to 1060 of FIG. 15 . For example, the wireless devices (e.g., 100 and 200 of FIG. 14 ) may receive radio signals from the exterior through the antenna ports/transceivers. The received radio signals may be converted into baseband signals through signal restorers. To this end, the signal restorers may include frequency downlink converters, Analog-to-Digital Converters (ADCs), CP remover, and Fast Fourier Transform (FFT) modules. Next, the baseband signals may be restored to codewords through a resource demapping procedure, a postcoding procedure, a demodulation processor, and a descrambling procedure. The codewords may be restored to original information blocks through decoding. Therefore, a signal processing circuit (not illustrated) for a reception signal may include signal restorers, resource demappers, a postcoder, demodulators, descramblers, and decoders.

FIG. 16 shows another example of a wireless device, based on an embodiment of the present disclosure. The wireless device may be implemented in various forms according to a use-case/service (refer to FIG. 13 ). The embodiment of FIG. 16 may be combined with various embodiments of the present disclosure.

Referring to FIG. 16 , wireless devices 100 and 200 may correspond to the wireless devices 100 and 200 of FIG. 14 and may be configured by various elements, components, units/portions, and/or modules. For example, each of the wireless devices 100 and 200 may include a communication unit 110, a control unit 120, a memory unit 130, and additional components 140. The communication unit may include a communication circuit 112 and transceiver(s) 114. For example, the communication circuit 112 may include the one or more processors 102 and 202 and/or the one or more memories 104 and 204 of FIG. 14 . For example, the transceiver(s) 114 may include the one or more transceivers 106 and 206 and/or the one or more antennas 108 and 208 of FIG. 14 . The control unit 120 is electrically connected to the communication unit 110, the memory 130, and the additional components 140 and controls overall operation of the wireless devices. For example, the control unit 120 may control an electric/mechanical operation of the wireless device based on programs/code/commands/information stored in the memory unit 130. The control unit 120 may transmit the information stored in the memory unit 130 to the exterior (e.g., other communication devices) via the communication unit 110 through a wireless/wired interface or store, in the memory unit 130, information received through the wireless/wired interface from the exterior (e.g., other communication devices) via the communication unit 110.

The additional components 140 may be variously configured according to types of wireless devices. For example, the additional components 140 may include at least one of a power unit/battery, input/output (I/O) unit, a driving unit, and a computing unit. The wireless device may be implemented in the form of, without being limited to, the robot (100 a of FIG. 13 ), the vehicles (100 b-1 and 100 b-2 of FIG. 13 ), the XR device (100 c of FIG. 13 ), the hand-held device (100 d of FIG. 13 ), the home appliance (100 e of FIG. 13 ), the IoT device (100 f of FIG. 13 ), a digital broadcast terminal, a hologram device, a public safety device, an MTC device, a medicine device, a fintech device (or a finance device), a security device, a climate/environment device, the AI server/device (400 of FIG. 13 ), the BSs (200 of FIG. 13 ), a network node, etc. The wireless device may be used in a mobile or fixed place according to a use-example/service.

In FIG. 16 , the entirety of the various elements, components, units/portions, and/or modules in the wireless devices 100 and 200 may be connected to each other through a wired interface or at least a part thereof may be wirelessly connected through the communication unit 110. For example, in each of the wireless devices 100 and 200, the control unit 120 and the communication unit 110 may be connected by wire and the control unit 120 and first units (e.g., 130 and 140) may be wirelessly connected through the communication unit 110. Each element, component, unit/portion, and/or module within the wireless devices 100 and 200 may further include one or more elements. For example, the control unit 120 may be configured by a set of one or more processors. As an example, the control unit 120 may be configured by a set of a communication control processor, an application processor, an Electronic Control Unit (ECU), a graphical processing unit, and a memory control processor. As another example, the memory 130 may be configured by a Random Access Memory (RAM), a Dynamic RAM (DRAM), a Read Only Memory (ROM)), a flash memory, a volatile memory, a non-volatile memory, and/or a combination thereof.

Hereinafter, an example of implementing FIG. 16 will be described in detail with reference to the drawings.

FIG. 17 shows a hand-held device, based on an embodiment of the present disclosure. The hand-held device may include a smartphone, a smartpad, a wearable device (e.g., a smartwatch or a smartglasses), or a portable computer (e.g., a notebook). The hand-held device may be referred to as a mobile station (MS), a user terminal (UT), a Mobile Subscriber Station (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), or a Wireless Terminal (WT). The embodiment of FIG. 17 may be combined with various embodiments of the present disclosure.

Referring to FIG. 17 , a hand-held device 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a memory unit 130, a power supply unit 140 a, an interface unit 140 b, and an I/O unit 140 c. The antenna unit 108 may be configured as a part of the communication unit 110. Blocks 110 to 130/140 a to 140 c correspond to the blocks 110 to 130/140 of FIG. 16 , respectively.

The communication unit 110 may transmit and receive signals (e.g., data and control signals) to and from other wireless devices or BSs. The control unit 120 may perform various operations by controlling constituent elements of the hand-held device 100. The control unit 120 may include an Application Processor (AP). The memory unit 130 may store data/parameters/programs/code/commands needed to drive the hand-held device 100. The memory unit 130 may store input/output data/information. The power supply unit 140 a may supply power to the hand-held device 100 and include a wired/wireless charging circuit, a battery, etc. The interface unit 140 b may support connection of the hand-held device 100 to other external devices. The interface unit 140 b may include various ports (e.g., an audio I/O port and a video I/O port) for connection with external devices. The I/O unit 140 c may input or output video information/signals, audio information/signals, data, and/or information input by a user. The I/O unit 140 c may include a camera, a microphone, a user input unit, a display unit 140 d, a speaker, and/or a haptic module.

As an example, in the case of data communication, the I/O unit 140 c may acquire information/signals (e.g., touch, text, voice, images, or video) input by a user and the acquired information/signals may be stored in the memory unit 130. The communication unit 110 may convert the information/signals stored in the memory into radio signals and transmit the converted radio signals to other wireless devices directly or to a BS. The communication unit 110 may receive radio signals from other wireless devices or the BS and then restore the received radio signals into original information/signals. The restored information/signals may be stored in the memory unit 130 and may be output as various types (e.g., text, voice, images, video, or haptic) through the I/O unit 140 c.

FIG. 18 shows a vehicle or an autonomous vehicle, based on an embodiment of the present disclosure. The vehicle or autonomous vehicle may be implemented by a mobile robot, a car, a train, a manned/unmanned Aerial Vehicle (AV), a ship, etc. The embodiment of FIG. 18 may be combined with various embodiments of the present disclosure.

Referring to FIG. 18 , a vehicle or autonomous vehicle 100 may include an antenna unit 108, a communication unit 110, a control unit 120, a driving unit 140 a, a power supply unit 140 b, a sensor unit 140 c, and an autonomous driving unit 140 d. The antenna unit 108 may be configured as a part of the communication unit 110. The blocks 110/130/140 a to 140 d correspond to the blocks 110/130/140 of FIG. 16 , respectively.

The communication unit 110 may transmit and receive signals (e.g., data and control signals) to and from external devices such as other vehicles, BSs (e.g., gNBs and road side units), and servers. The control unit 120 may perform various operations by controlling elements of the vehicle or the autonomous vehicle 100. The control unit 120 may include an Electronic Control Unit (ECU). The driving unit 140 a may cause the vehicle or the autonomous vehicle 100 to drive on a road. The driving unit 140 a may include an engine, a motor, a powertrain, a wheel, a brake, a steering device, etc. The power supply unit 140 b may supply power to the vehicle or the autonomous vehicle 100 and include a wired/wireless charging circuit, a battery, etc. The sensor unit 140 c may acquire a vehicle state, ambient environment information, user information, etc. The sensor unit 140 c may include an Inertial Measurement Unit (IMU) sensor, a collision sensor, a wheel sensor, a speed sensor, a slope sensor, a weight sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, an illumination sensor, a pedal position sensor, etc. The autonomous driving unit 140 d may implement technology for maintaining a lane on which a vehicle is driving, technology for automatically adjusting speed, such as adaptive cruise control, technology for autonomously driving along a determined path, technology for driving by automatically setting a path if a destination is set, and the like.

For example, the communication unit 110 may receive map data, traffic information data, etc. from an external server. The autonomous driving unit 140 d may generate an autonomous driving path and a driving plan from the obtained data. The control unit 120 may control the driving unit 140 a such that the vehicle or the autonomous vehicle 100 may move along the autonomous driving path according to the driving plan (e.g., speed/direction control). In the middle of autonomous driving, the communication unit 110 may aperiodically/periodically acquire recent traffic information data from the external server and acquire surrounding traffic information data from neighboring vehicles. In the middle of autonomous driving, the sensor unit 140 c may obtain a vehicle state and/or surrounding environment information. The autonomous driving unit 140 d may update the autonomous driving path and the driving plan based on the newly obtained data/information. The communication unit 110 may transfer information about a vehicle position, the autonomous driving path, and/or the driving plan to the external server. The external server may predict traffic information data using AI technology, etc., based on the information collected from vehicles or autonomous vehicles and provide the predicted traffic information data to the vehicles or the autonomous vehicles.

Claims in the present description can be combined in a various way. For instance, technical features in method claims of the present description can be combined to be implemented or performed in an apparatus, and technical features in apparatus claims can be combined to be implemented or performed in a method. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in an apparatus. Further, technical features in method claim(s) and apparatus claim(s) can be combined to be implemented or performed in a method. 

What is claimed is:
 1. A method for performing wireless communication by a first device, the method comprising: obtaining a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receiving, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receiving, from the second device through the PSSCH, the second SCI and data; determining a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and starting the SL DRX retransmission timer.
 2. The method of claim 1, wherein the value of the SL DRX HARQ RTT timer represents a minimum duration before SL HARQ retransmission is expected by the first device.
 3. The method of claim 1, wherein the value of the SL DRX retransmission timer represents a maximum duration until SL retransmission is received.
 4. The method of claim 1, wherein the value of the SL DRX retransmission timer and the value of the SL DRX HARQ RTT timer are configured per SL process.
 5. The method of claim 1, further comprising: starting the SL DRX HARQ RTT timer in a slot following an end of reception of the PSSCH.
 6. The method of claim 5, wherein the SL DRX retransmission timer is started based on expiration of the SL DRX HARQ RTT timer.
 7. The method of claim 1, wherein, based on that (i) the information related to the next retransmission resource is not included in the first SCI and (ii) a physical sidelink feedback channel (PSFCH) resource is not configured, the value of the SL DRX HARQ RTT timer is determined as zero.
 8. The method of claim 1, wherein the first SCI includes information related to time resource assignment, and wherein the information related to the time resource assignment includes only time information for the PSSCH.
 9. The method of claim 1, further comprising: receiving, from a base station, information for determining the value of the SL DRX HARQ RTT timer as zero.
 10. The method of claim 9, wherein, based on (i) the first SCI not including the information related to the next retransmission resource and (ii) the information for determining the value of the SL DRX HARQ RTT timer as zero, the value of the SL DRX HARQ RTT timer is determined as zero.
 11. The method of claim 10, wherein the information for determining the value of the SL DRX HARQ RTT timer as zero is information related to a SL resource pool for which a PSFCH is not configured.
 12. The method of claim 9, wherein the information for determining the value of the SL DRX HARQ RTT timer as zero is received from the base station through a radio resource control (RRC) message.
 13. The method of claim 1, wherein a time during which the SL DRX retransmission timer is running is an active time of the first device.
 14. A first device adapted to perform wireless communication, the first device comprising: one or more memories storing instructions; one or more transceivers; and one or more processors connected to the one or more memories and the one or more transceivers, wherein the one or more processors execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; control the one or more transceivers to receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); control the one or more transceivers to receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.
 15. The first device of claim 14, wherein the value of the SL DRX HARQ RTT timer represents a minimum duration before SL HARQ retransmission is expected by the first device.
 16. The first device of claim 14, wherein the value of the SL DRX retransmission timer represents a maximum duration until SL retransmission is received.
 17. The first device of claim 14, wherein the value of the SL DRX retransmission timer and the value of the SL DRX HARQ RTT timer are configured per SL process.
 18. A processing device adapted to control a first device, the processing device comprising: one or more processors; and one or more memories operably connected to the one or more processors and storing instructions, wherein the one or more processors execute the instructions to: obtain a sidelink (SL) discontinuous reception (DRX) configuration including a value of a SL DRX retransmission timer; receive, from a second device through a physical sidelink control channel (PSCCH), first sidelink control information (SCI) for scheduling of second SCI and a physical sidelink shared channel (PSSCH); receive, from the second device through the PSSCH, the second SCI and data; determine a value of a SL DRX hybrid automatic repeat request (HARQ) round trip time (RTT) timer as zero, based on that information related to a next retransmission resource is not included in the first SCI; and start the SL DRX retransmission timer.
 19. The processing device of claim 18, wherein the value of the SL DRX HARQ RTT timer represents a minimum duration before SL HARQ retransmission is expected by the first device.
 20. The processing device of claim 18, wherein the value of the SL DRX retransmission timer represents a maximum duration until SL retransmission is received. 